Many conventional search engines are designed to provide a series of responsive documents to a user based on a search query. However, a user of a search engine is not always looking for a document. Instead, many user queries are based on a user desire to learn a particular fact or a group of related facts. For example, a user may want to know the height of a mountain, the population of a city, or the names of books written by an author. The document listings provided by conventional search engines may provide such an answer, but to find the answer the user has to take the additional steps of accessing the document and reviewing the document for the desired information.